reading chars in raw mode with Ioctl .. How ?

[Robert Felps]

In <24905 at uflorida.cis.ufl.EDU> kcw at beach.cis.ufl.edu (Ken Whedbee) writes:

>I m looking for example code (bsd derivative .. SunOS perferably) that
>reads characters one at a time instead of buffering the chars until a
>newline like the read() system call.

>I understand that ioctl() can do this by setting the terminal into
>raw mode such that no pre-processing of the input takes place.  There's
>example code of how to do this on pg. 340 in Bach's book.  But alas,
>this is system V code.

>Does anyone know of or can give me an example in bsd ?

This should do BSD or SV single character input.

---------------------------------------------------------------------------
/*
This program resets the tty driver to allow single character input.
It provides for single character input in shell scripts.

Usage:
	ANSWER=`getsks`

To compile and install:

	cc -D[BSD|SV] getsinglekey.c -o getsks
	chmod 555 getsks
	cp getsks /usr/local/bin
 */

#include <sys/types.h>
#include <signal.h>

#ifdef BSD
#include <sgtty.h>
	/* include the BSD terminal handling header file. */
struct sgttyb new, old; /* BSD term-info structure */
#else
	/* include the System V terminal handling header file. */
#include <termio.h>
struct termio new, old; /* SYSV term-info structure */
#define gtty(fd,arg)   (ioctl(fd, TCGETA, arg))
#define stty(fd,arg)   (ioctl(fd, TCSETA, arg))
#endif

main()
{
  int c;

  gtty(0,&old);
  gtty(0,&new);

#ifdef BSD /* set "raw" mode for BSD */
  new.sg_flags &= ~(ECHO|CRMOD);
  new.sg_flags |= RAW;
#else
  new.c_iflag &= ~(INLCR|ICRNL|IUCLC|ISTRIP|IXON|BRKINT);
  new.c_oflag &= ~OPOST;
  new.c_lflag &= ~(ICANON|ISIG|ECHO);
  new.c_cc[VMIN]  = 1;
  new.c_cc[VTIME] = 1;
#endif

  stty(0,&new);

  if (c=getchar()) {
    stty(0,&old);
    putchar(c);
    exit(0);
  }
}
---------------------------------------------------------------------------

Hope it helps,

Robert Felps                                felps at convex.com
Convex Computer Corp                        OS System Specialist
3000 Waterview Parkway                      Tech. Assistant Ctr
Richardson, Tx.  75083                      1(800) 952-0379